In recent years, image display apparatus typified by a liquid crystal display apparatus and an organic EL display apparatus have been rapidly gaining more widespread use. In the image display apparatus, a polarizing plate and a retardation plate are typically used. In practical use, a polarizing plate with a retardation layer, in which the polarizing plate and the retardation plate are integrated, is widely used (for example, Patent Literature 1). In this connection, recently, along with an increasing demand for thinning of the image display apparatus, there has also been an increasing demand for thinning of the polarizing plate with a retardation layer. However, when an attempt is made for the thinning of the polarizing plate with a retardation layer, there arises a problem in that its durability (typically durability under high temperature and high humidity) becomes insufficient. The problem becomes more remarkable as the polarizing plate with a retardation layer becomes thinner.